Patent GB-485287-A (GB)
Title: Improvements in carburetters for internal combustion engines
IPC: F02M69/00
Filed: 1936-08-17
Abstract: 485,287. Spray carburetters; fluid-actuated valves. SOC. GENERALE DES CARBURATEURS ZENITH. Aug. 17, 1936, No. 22638. Convention date, Aug. 24, 1935. [Class 7 (iii)] [Also in Group XXIX] In a diaphragm fuel-pressure regulator, which includes a depression chamber communicating bv a depression passage with the induction passage of the carburetter and having a movable partition connected to the diaphragm of the regulator, the connection between the partition and the diaphragm is such that the depression acting on the partition increases the balance pressure in the regulator. The valve of the regulator may remain open when the engine is at rest and the fuel supply pressure to the regulator is higher than the balance pressure in the regulator in all operating conditions. An air passage connects the depression chamber with the air intake or the atmosphere either directly or through a compartment separated from the fuel bowl of the regulator by the diaphragm thereof. An anterior throttle valve 3 actuates a fuel needle valve 5 controlling the outlet of a fuel nozzle 4 which is supplied from a chamber 10. Fuel under pressure is fed to the chamber 10 past a valve 13 controlled by a diaphragm 12 disposed in a wall of the chamber to maintain in the chamber a predetermined pressure. The diaphragm 12 is connected through a rod 14 and lever 15, 16 with the diaphragm 23 of a depression chamber 20 open to the mixing chamber 1, adjacent the fuel nozzle 4, through a depression tube 21, the depression operating to lift the diaphragm 23 and open the fuel valve 13 to increase the fuel supply. The lever 15, 16 operates in an intermediate chamber 25 open to the atmosphere or the air inlet through a conduit 26. The pressure applied to the diaphragm 12 may be diminished by making the arm 16 of the lever 15, 16 shorter than the arm 15 or by inserting a valve in the depression tube 21 and connecting the depression chamber 20 through a restricted orifice to the air inlet, the depression in the chamber thus being some fraction of the carburetter depression. By providing similar connections for the intermediate chamber 25, the strength of the mixture may be varied, for example according to altitude; both chambers may be similarly controlled. As shown in Fig. 5, the depression chamber 20 is connected to the intermediate chamber 25, by a passage 35 and restricted orifice 36, instead of to the air inlet, the arrangement ensuring that the valve 33 in the depression tube 21 gives a constant enrich. ment of the fuel irrespective of the setting of the valve 29 associated with the intermediate chamber. The valve 29 may be controlled by a pressure sensitive device dependent upon the absolute pressure in the mixing chamber as described in Specification 471,508. In aviation carburetters, where it is desired to have a richer mixture at small and wide throttle openings and a mixture leaner than normal at medium openings, the arrangement shown in Fig. 7 is used. The intermediate chamber 25 communicates past a valve controlled by a pressure sensitive device 37 with the mixing chamber and the depression chamber 20 communicates therewith through a valve 42, conduit 45 and restricted orifice 44 and also through a passage 46 leading from the passage 45, valve 48, passage 53 and restricted orifice 54, the valve 48 having also a connection 52 to the mixing chamber 1. A rod 50 connects the valve 48 to the throttle valve 3. In operation, rich mixture required with the wide open throttle results from depression communicated to the chamber 20 through the passage 52, passages 56, 58 in the valve 48 and the passage 53 and also through the valve 42, if open, and the passage 45. If the valve 42 is closed, the passage 52, passages 56, 55 in the valve 48 and the passage 46 byepass it. At medium throttle openings, the passages 52, 53 and 46 are interrupted and normal mixture is supplied if the valve 42 is open or a leaner mixture if it is closed and the chamber 20 wholly isolated from the mixing chamber. At small throttle openings, passages 55, 58 and 57 replace the passages 56, 55, 58 in the valve 48 and rich mixture is supplied. The depression chamber 20 may bo adjacent the fuel chamber 10 and the chamber 25 be on the opposite side of the depression chamber. Specifications 378,025, 378,038, 382,948, and 464,327 also are referred to.